Westford to update their LED street lights to a color better for the night sky

Joy Richard jrichard@wickedlocal.com

Wednesday

Aug 22, 2018 at 3:47 PMAug 28, 2018 at 2:15 PM

With more towns transitioning their street and outdoor lighting to the more Earth-friendly LED lights, there has proven one hitch in the money-saving and greener change over: The intensity and color of the lights is obscuring local researcher's view of the night sky.

Speaking with Westford-based Wallace Astrophysical Observatory Manager Tim Brothers, it was clear that while the idea of heading over to environmentally friendly lighting is a positive move for town, the downside is the kind of lights being installed are so bright it is making research harder for those studying the solar system. He said it all comes down to how many Kelvin, a term you might remember from high school chemistry as a measure of temperature, a light emits.

"A measure of the color of a light source relative to a black-body at a particular temperature expressed in degrees Kelvin (K,)" according to The LED Light's website. "Warm, white LED lamps have a color temperature between 2,700 and 3,500K. Lamps rated between 5,000K and 6,000K are viewed as white, while lamps above 6,000K tend to have a blue cast."

When it comes to sky-friendly lights, the blue cast of most street lamps is a no-go, and has been affecting the night sky for at least the last decade, according to Brothers. Upgrading to a "warmer" Kelvin number, installing shields on the lamps to direct the light downward, or having a manual control to turn them on, off, or in a different direction can in the end make a huge difference.

"I have been working [at the observatory] since 2009 and we have seen a steady progression in sky brightening," said Brother. "Not the entire sky, just the direction of the sky towards areas of development."

He gave examples such as the Boston Road area, Interstate 495, and a few in the area car dealerships. Brothers said this has happened in the past five years.

"Now we’re finding even on clear, moonless nights it is harder to see the Milky Way," said Brothers.

They can see the changes due to the sensors they have at the observatory, which have been taking readings of the sky every minute for the last five years.

Brothers said, "There is a really good reason to convert to LED. It is far more efficient and cheap to produce, those are both good things. We have a tendency in our society to over-light things. Instead of replacing one-for-one, we are increasing the number of lights."

Brothers said he is so pleased to have been able speak with Westford Assistant Town Manager Eric Heidman, making the suggestion of changing the lights to a lower measurement of Kelvins when they upgrade their 1,200 lights at the end of this year.

Heidman said the town was able to procure two grants to help update street lighting with an end-date for the project set for December. He said the town is still working to purchase some street lights from National Grid, those are not yet LED lamps.

The grants are from Green Communities for $250,000 and Metro Area Planning, Rapid Retrofit program for $90,000. He said they are working with the designers at Light Smart on the light update project.

"We expressed the concerns [Brothers shared] with designers and they had no issues when it came to purchasing lights below 3,000K," said Heidman.

Brothers said he is excited to see how the lower intensity lights change how they see the sky at the observatory. He said he also hopes Westford's choices will influence other towns in the area when they convert their current street lights to LED fixtures.

"We had a really great, frank discussion" said Brothers adding these updates could be used as a part of an "example project" for the scientists at the observatory. "It is healthier for the community and a great example for other towns. We are not against development, just bad development."

In Littleton, Electric Light Department Assistant General Manager David Ketchen said the town converted 755 street lamps from 2016 to 2017. They are 4,000K, which is between warm and blue light. He said while they don't have a timer on the "cobra-head" style lamp he said they are equipped with a cell, which keeps the light off when sun light is detected. He said during the design phase they also worked to make sure the light wouldn't "leak" into yards and would stay pointed only at the ground, which was hoped to help keep its affect on the sky minimal.